I put no credibility in anything Jeff Duncan says.
That being said, of course the team isn't fully confident in Penning. He has clear struggles in pass protection, but he's still likely the best RT they have on the team. Should they have gotten another starting RT to compete with Penning? Absolutely, but that ship has long since sailed. So, confident or not, he's the RT. The hope is that he continues to improve the way he has over the preseason.